chmod octal file - change the permissions of file to octal, which can be found separately for user, group, and world by adding:
• 4 - read (r)
• 2 - write (w)
• 1 - execute (x)
Examples:
chmod 777 - read, write, execute for all
chmod 755 - rwx for owner, rx for group and world
For more options, see man chmod.

SSH

ssh user@host - connect to host as user

ssh -p port user@host - connect to host on port, port as user

ssh-copy-id user@host -add your key to host for user to enable a keyed or passwordless login